Fremont Mine (Fremont-Grover Mine; Fremont-Gover; Fremont-Gover Inc.; North Gover; Foremont; Gopher; Loyal lode), New Chicago, Jackson-Plymouth Mining District, Amador County, California, USAi

Regional Level Types
Fremont Mine (Fremont-Grover Mine; Fremont-Gover; Fremont-Gover Inc.; North Gover; Foremont; Gopher; Loyal lode)	Mine
New Chicago	- not defined -
Jackson-Plymouth Mining District	Mining District
Amador County	County
California	State
USA	Country

A former Au-As mine located in the SW¼ secs. 24 & 25, T7N, R10E, MDM, 0.5 km (0.3 mile) ENE of New Chicago and about 1 mile E of Drytown, 1.5 miles N of Amador City, and 3 miles S of Plymouth. Discovered before 1867. Operated by Fremont Gover Co., C/O C. B. Braun. This mine includes the Loyal lode. Operated in the 1880's, 1890's, during the period 1920 to 1923, and the period 1937 to 1940. MRDS database stated accuracy for this location is 1,000 meters. This mine group was worked intermittently until 1940. The "Gopher Mine" shown on USGS Sutter Creek quadrangle map should probably be the "Gover."

The Loyal lode, part of this mine, was worked prior to 1867. The Fremont and Gover Co. was formed in 1872 and was worked intermittently until 1940. Total production was in excess of $5,000,000 (period values). The claims covered 4,200 feet along the strike of the Mother Lode, including the Fremont, Gover, Loyal lode Mine and mill site, North Gover, Bona Esperanza Mine and mill site, half interest in the Bona Fortuna Mine and mill site and several parcels of non-mineral land.

The Freemont-Gover Mine is located one and one-half miles north of Amador City in the famous Mother Lode Gold Belt of the Sierra Nevada foothills. The Fremont and Gover mines operated independently until they were merged in 1872. The mine is part of the Jackson - Plymouth district, which was the most productive district of the Mother Lode belt with an estimated total production of about $180 million (Clark, 1970). The Fremont-Gover Mine is credited with producing about $5.0 million. (Clark, 1970)

At its peak, the Fremont-Gover Mine covered 4200 feet along the strike of the Mother Lode, and included the Fremont, Gover, and North Gover claims, Loyal Lode Mine and mill site, Bona Esperanza Quartz Mine and mill site, one-half interest in the Bona Fortuna Quartz Mine and mill site, and several parcels of non-mineral land (Logan, 1934). There is little information about the earliest history of the properties and later histories are sketchy, but they are known to have been operated independently until their later consolidation.

The Loyal Lode mine is known to have been in operation prior to 1867 (Carlson & Clark, 1954). Work on the Loyal Lode claim had been confined to mining rich stringers and small high-grade bodies of or at or near the surface. The surface quartz ore was originally worked in arrastras which were replaced by a 20-stamp mill sometime before 1867. By 1876, the mine was idled at a depth of 100 feet.

The Fremont and Gover mines were also early producers with Gover Mine having been partially mined to a depth of 1500 feet (1050 feet vertical) when it was shut down after its 40-stamp mill was destroyed by fire. The Fremont and North Gover claims also were largely undeveloped. In 1872, the Fremont and Gover Company was formed and consolidated these two properties. During the 1880s and 1890s, work focused primarily on the Gover claim (Logan, 1934). The only figures available indicate an annual output of from $50,000 to $70,000 in the 1880's and early 1890's with the last reported production in 1894. In 1888, ore yielded $9-$13 a ton (Logan, 1934).

The Loyal Lode Mine was reopened in the 1880s and in 1886 it was producing ore that yielded $7-$8 a ton in free gold. In 1888, two ore shoots were reported, one 200 feet long and another 80 feet long. Fourteen men were working and the stamp mill was crushing 15 tons a day (Logan, 1934). The 200-foot ore shoot had been opened its full length and was reportedly 20 feet wide. The work was done through 3 adits, the deepest 300 feet long and 120 feet deep at the face. There are no later records, and no details of the output (Logan, 1934).

The Fremont shaft was started in 1900 and in 1903, a new 40-stamp mill was erected. The upper levels from 400 to 700 feet deep, developed the Mother Lode contact vein. From the 800-foot level downward, the gray ore associated with the East vein was mined. Fremont Consolidated Mining Company worked to a depth of 2950 feet on a 51? incline. The mine was closed in December, 1918 due to excessive costs and a labor scarcity brought on by World War I. Late in 1920, the Metals Exploration Company began unwatering the mine and prospected it from 1920 - 1923, producing some ore. In the latter year, 20 stamps were put in operation but work was stopped in August. A new Company, Fremont-Gover Mines Company, was incoprporated at once by former employees, but they were unable to finance work for long, and quit in 1925 after only a small amount of work. Shortly after, Black Hills Fremont Mines Company did a little work in a shallow adit and a winze 100 feet deep on the Gover claim 600 feet north of Gover shaft. The venture was short lived (Logan, 1934). Between 1900 and 1925, there was a reported output of about 930,000 tons which is said to have averaged about $4 a ton recovered. Shortly after, Black Hills, Fremont Mines Company did a little work in an adit and in a 100-foot winze (Carlson & Clark, 1954).

Early in 1937, the property was reopened by Amador Mother Lode Mining Company (Carlson & Clark, 1954). In September 1937, the property was purchased by the Fremont Gover Company who operated it until April 1940. The Gover shaft was reopened to the 865 level and the Fremont shaft to the 770 level. Several thousand feet of new drifts, crosscuts and raises were driven (Carlson & Clark, 1954).

Total production from the combined properties was about $5 million from which $316,000.00 in dividends are known top have been paid.

Mineralization is a vein deposit deposit (Mineral occurrence model information: Model code: 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27) hosted in Late Jurassic slate, greenstone & schist of the Mariposa Formation. The ore body is tabular, pinch & swell in form, strikes N25W and dips 50E. Controls for ore emplacement included fault-fissures and ore shoots within mesothermal Au-bearing quartz veins. The average thickness of the quartz vein is 6 feet and gold ore produced from and near the vein occurred in stringers, pockets and in auriferous greenstone. The vein walls are slate to the 170 foot level. The hanging wall is greenstone and the footwall is slate from the 170 foot level to the 600 foot level. Below that depth, both walls are greenstone. Ore Materials include free-milling quarts with associated auriferous pyrite and arsenopyrite. Hydrothermal alteration of greenstone and schist wallrocks yileded enough disseminated auriferous pyrite and arsenopyrite to constitute low-grade ore. Local rocks include Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains).

Regional geologic structures include the Bear Mountains Fault zone and the Melones Fault zone. Local structures include a reverse fault with 375 feet of displacement.

The Fremont-Gover mine developed two veins, the Mother Lode vein (or contact vein) and the East vein (or gray ore fissure), as well as large bodies of mineralized greenstone and schist (gray ore).

The Mother Lode and the East veins are separated by a zone of slate that narrowed to only a gouge in places, but thickened to as much as 90 feet in places. The Mother Lode vein occupies a fault fissure striking N 20?- 25? W and dipping 45?- 50? east. The fault displays a measurable offset of 375 feet. From the surface to the 170 feet, the vein is in slate while from that depth to the 600-foot level, the vein has a greenstone hanging wall and a slate footwall. Below the 600-foot level, the vein is in greenstone. The vein is generally narrow in the slates, but widens with depth, 50 to 60 feet being commonly reached (Knopf, 1929). The contact vein next to the greenstone produced the best ore. Gold was produced from pockets in quartz stringers extending into greenstone. Auriferous pyrite and arsenopyrite were common. The principal Mother Lode vein ore shoot was about 300 feet long by 20 feet wide and pinched out at a depth of 800 feet. While the Mother Lode vein continued at depth, it was of too low a grade to extract
The East vein or gray ore fissure vein occupies a facture that strikes approximately N 10? W and dips 55? E. The vein is composed of slate and quartz exhibiting much auxiliary fissuring and shattering. Above the 900-foot level, it is a well-defined quartz vein, generally narrow and containing a foot or so of gouge. In some places, however, it expands to large bodies of coarse white quartz up to 6 feet thick that were stoped. The largest ore shoot was 280 feet long. Below the 900-foot level and extending to the 2300-foot level, the East vein entered hanging wall greenstone. As the vein entered greenstone, the nature of the ore changed to a body of mineralized schist and greenstone gray ore in the enclosing wall rocks. This ore was composed to hydrothermally altered schist and greenstone carrying 3% to 5% disseminated auriferous sulfides, mostly pyrite and arsenopyrite, which carried three fourths to five sixths of the gold. The largest gray ore shoot was nearly 300 feet long, extending to the 2300-foot level. It averaged 30 feet wide, but thickened to as much as 70 feet (Logan, 1927). The ore shoot consisted of a large mass of auriferous greenstone and schist occupying the wedge between the Mother Lode vein and the East vein at their junction. Contained sulfides were chiefly pyrite and arsenopyrite with trace amounts of galena and sphalerite. Several other lenses of gray ore were mined between the 800 and 2500-foot levels. These varied in width, their wider sections being 10-25 feet thick, with stope lengths up to 100 feet (Logan, 1934). The gray ore bodies yielded the bulk of the output from the Fremont-Gover Mine. Gray ore values varied from a trace to $20 a ton, but in general were quite low. (Knopf, 1929).

Workings include underground openings. The Gover shaft is 2,500 feet deep; the Fremont shaft is 2,950 feet, and is inclined 51 degrees. There was extensive drifting in both shafts. The Gover Mine was principally worked initially in the late 1880's and early 1890's. The Fremont shaft was begun in 1903.

The Fremont-Gover Mine was developed through the Fremont shaft extending 2950 feet on a 51? incline, and the Gover shaft, an inclined shaft 1500 feet in length located 1430 feet north of the Fremont (Knopf, 1929). The 1500-foot level of the Gover connected with the 1350-foot level of the Fremont. Levels were 200 feet apart. Drifting was extensive from both shafts aggregating several miles, the vein having been followed 2500 feet north from the Fremont shaft. Mining was done partly by square setting and partly with stulls, all stopes being filled (Carlson & Clark, 1954).

The mill contained 40 stamps. Concentration was on Frue vanners. The mill handled about 200 tons daily and produced about 200 tons a month of concentrate worth $65 to $100 a ton. Recovery was about 85% of assayed values. From 1914 to 1920, the tailings were worked on a royalty basis by the California Slimes Concentrating Company. Tailings were treated by regrinding, concentration, and cyanidation (Carlson & Clark, 1954).

Production data are found in: Carlson, D.W. & W.B. Clark (1954).

Clark (1970) reported that the Fremont-Gover Mine produced $5.0 million (period values).

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Link to USGS MRDS:	10310615

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